This invention relates to a clutch and release bearing assembly and in particular to an assembly in which an adjuster mechanism is included to compensate for wear in the clutch.
It is known from GB No. 1544814 to provide a release bearing assembly for a clutch in which an adjuster mechanism is provided to compensate for wear of the clutch. In GB No. 1544814 the assembly comprises a first member operatively connected to releasing means of the clutch and having a screw threaded surface, a second member movable relative to the first member and being operatively connectable to an operator controlled release member, an element in threaded engagement with the first member and through which clutch release forces are transmitted from the second member to the first member, said element being prevented from rotating relative to the first member during clutch release, abutment means on the clutch for releasing the element when the second member reaches a predetermined position to allow the element to rotate relative to the first member thereby allowing the first member to move axially relative to the second member, and resilient means for urging the second member towards the clutch. However, the resilient means urges the second member towards the clutch through the outer race of a clutch release bearing. Therefore, any backlash in the clutch release mechanism has to be taken up on clutch release by the operator controlled release member which is disadvantageous. It is an object of the invention to provide an assembly which reduces that disadvantage.
According to one aspect of the invention there is provided a clutch and release bearing assembly comprising a first member operatively connected to releasing means of the clutch and having a screw threaded surface, a second member movable relative to the first member and being operatively connectable to an operator controlled release member, an element in threaded engagement with the first member and through which clutch release forces are transmitted from the second member to the first member, said element being prevented from rotating relative to the first member during clutch release, abutment means on the clutch for releasing the element when the second member reaches a predetermined position to allow the element to rotate relative to the first member thereby allowing the first member to move axially relative to the second member, and resilient means for urging the second member towards the clutch and which acts between the second member and means on the clutch.
With such an arrangement load can be applied directly to the second member rather than through an intermediate releasing mechanism.
Preferably, said means on the clutch is part of said abutment means.
The resilient means may be a tension spring having one end secured to the second member.
The abutment means may define a thrust surface for said element. The thrust surface may form a bearing surface which engages a face on the element.
The abutment means may define a surface for co-operation with said second member.
The abutment means may include an annular plate.
Preferably the abutment means includes a bearing member for co-operation with the collar. The aforesaid thrust surface may be formed on the bearing member and/or where the abutment means defines a surface for co-operation with said second member, said surface may be formed on the bearing member.
The bearing surface and the surface for co-operation with said second member are preferably spaced apart axially of the assembly.
The first and second members and said means on the clutch may be rotatable with the clutch.
Preferably locking means is provided between a surface on the element and a surface of the second member which locks the element against rotation relative to the first member during clutch release.
The use of such locking means is advantageous as it avoids the need to provide accurately machined co-operating cone-clutch surfaces as disclosed in GB No. 1544814.
In that respect and according to another aspect of the invention, there is provided a clutch and release bearing assembly comprising a first member operatively connected to release means of the clutch and having a screw threaded surface, a second member movable relative to the first member and being operatively connectable to an operator controlled release member and element in threaded engagement with the first member and through which clutch release forces are transmitted from the second member to the first member, said element being prevented from rotating relative to the first member during clutch release, abutment means on the clutch for releasing the element when the second member reaches a predetermined position to allow the element to rotate relative to the first member thereby allowing the first member to move axially relative to the second member, resilient means for urging the second member towqrds the clutch, and locking means provided between a surface on the element and a surface of the second member which locks the element against rotation relative to the first member during clutch release.
A resilient member may be arranged between said element and second member to assist in preventing the element rotating relative to the first member during clutch release. The resilient member may be an annular spring which is axially deformed into e.g. a wavy configuration.
The locking means is preferably radially movable and may comprise a snap ring, circlip or the like. The locking means may be of circular cross-section.
The said surface on the element and/or the surface of the second member may of frusto-conical form.
Preferably, the element is released following abutment of the element. Abutment of the element against said abutment means preferably releases the locking member.
According to a further aspect of the invention there is provided a clutch and release bearing assembly comprising a first member operatively connected to releasing means of the clutch and having a screw threaded surface, a second member movable relative to the first member and being operatively connectable to an operator controlled release member, an element in threaded engagement with the first member and through which clutch release forces are transmitted from the second member to the first member, said element being prevented from rotating relative to the first member during clutch release, abutment means on the clutch for releasing the element when the second member reaches a predetermined position to allow the element to rotate relative to the first member thereby allowing the first member to move axially relative to the second member and resilient means for urging the second member towards the clutch, said element being releasable following abutment of the element against said abutment means.
The second member in any previous aspect of the invention may be prevented from relative rotation with respect to the first member by a projection on one of the members engaged with a recess in the other of the members. Such a projection may be a peg or pin connected to the second member or the first member.
The invention will now be described by way of example with reference to the accompanying drawings of which: